It is known to provide so-called xe2x80x98rumble stripsxe2x80x99 alongside major roads, in the form of spaced-apart ribs of white material extending transversely to the flow of traffic. When a vehicle on the road veers excessively towards the edge of the road, its wheels come into contact with the rumble strip. The contact of the tyre with the ribs causes the tyre to bounce from one rib to another. The resultant movement of the steering wheel, and the noise produced by the wheel suspension, draws the attention of the driver to the fact that his vehicle is in danger of running off the road. Such rumble strips have been produced by the application of a hot thermoplastic material to the road surface and, while it is still plastic, applying a mould to the top surface of the strip to form a short series of ribs extending upwardly from the top surface of the strip. Another known technique is to apply a two-component material to form the ribs. The application of thermoplastic material needs costly equipment, so that both known techniques are relatively expensive, and also provides no visual signals to drivers, as light is reflected both from the ribs and from the intervening strip.
The present invention aims at providing a machine by means of which a thick layer of a water-based paint is blasted at a specific location on a road surface to form an upstanding rib of material which offers a visual contrast with the adjacent road surface, and which is of sufficient height to form one of the ribs of a rumble strip.
Accordingly, the present invention provides a road-marking machine that is as claimed in the appended claims.